1. Field of the Invention
The present invention relates to a thermal compensating microwave dielectric ceramic composition, and more particularly a low-temperature sintering temperature compensating microwave dielectric ceramic composition which makes it possible to sinter at a low temperature ranging from 1050.degree. C. to 1250.degree. C., consisting of a composition of ZnTiO.sub.3 stoichiometrically combined with ZnO and TiO.sub.2 and (Zn.sub.1-X Mg.sub.X)TiO.sub.3 in which some of the ZnO of the ZnTiO.sub.3 is replaced with MgO.
2. Description of the Prior Art
Recently, communication equipments such as wireless telephone receivers and mobile phones, and electronic parts applied to transmitter/receivers for satellite communication are increasingly getting higher in frequency, smaller in size and lighter in weight. Accordingly, high frequency is being evolved from a conventional bulk type to a multilayer type which enables a surface mounting, and also to a composite module.
In electrical circuits, a ceramic dielectric is applied to a variety of objectives such as by-passing, coupling and filtering. Thermal compensating ceramic dielectric is mainly used to manufacture high frequency devices such as coupling circuits, filters and resonators.
Significant electrical properties applicable to the above objectives may include a high dielectric constant, a low dielectric loss, a high quality (Q) factor, a temperature coefficient of capacitance and/or resonant frequency, a high insulating resistance, a high mechanical strength, and a low thermal expansion coefficient.
What is more important in applying to a practical use properties such as timing and tuning respectively appropriate to a high frequency equipment may be a quality coefficient, a capacitance, and the stability of a resonant frequency. Further, in a tuning circuit, the resonant frequency requires a correspondence to or a compensation for environmental factors such as temperature, humidity, voltage and electric current.
A precise sintering having mechanical strength and dielectric property sufficient for serving as a device without an additional sintering agent is not obtained at a high sintering temperature ranging from 1300.degree. C. to 1600.degree. C. as shown in conventional high frequency dielectric compositions such as barium titanites: BaTi.sub.4 O.sub.9, Ba.sub.2 Ti.sub.4 O.sub.20 and Ba.sub.2 Ti.sub.5 O.sub.11, magnesium titanites:(Mg,Ca)TiO.sub.3, ZST:(Zn,Sn)TiO.sub.4, barium perovskites: Ba(Zn.sub.1/3 Nb.sub.2/3)O.sub.3, Ba(Zn.sub.1/3 Nb.sub.2/3)O.sub.3, Ba(Mg.sub.1/3 Nb.sub.2/3)O.sub.3 and Ba(Mg.sub.1/3 Ta.sub.2/3)O.sub.3, (Ca,Sr,Ba)ZrO.sub.3, and (Ca,Sr)(Li,Nb)Ti!O.sub.3.